JP2013530539A - High concentration P doped quantum dot solar cell by forced doping of INP and manufacturing method - Google Patents

Abstract

The present invention relates to a method for manufacturing a semiconductor quantum dot-sensitized solar cell.
In the manufacturing method of the present invention, after a semiconductor layer containing a group 4 element and InP is formed on an upper portion of a substrate, the substrate on which the semiconductor layer is formed is heat-treated to remove In (Indium). There is a feature including a quantum dot formation step of forming an n-type semiconductor quantum dot which is a group 4 element quantum dot doped with (phosphorus).
[Selection] Figure 3

Description

  The present invention relates to a semiconductor-based quantum dot solar cell and a method for manufacturing the same, and more particularly to a method for manufacturing a solar cell in which semiconductor quantum dots doped with P at a considerably high concentration are formed.

  In the case of solar elements, various materials other than silicon have been researched in order to reduce manufacturing costs and increase efficiency, but due to the characteristics of solar elements using semiconductor principles, solar elements based on silicon Compared with, the efficiency is considerably lower, the lifetime due to deterioration is short, and the actual market share is insignificant to 3% inside and outside.

  In the case of solar elements based on silicon, most of them use silicon single crystals and silicon polycrystals, and the cost of silicon materials and wafers when constructing a solar system exceeds 40% of the total construction cost. As a practical solution to this, efforts to reduce the amount of silicon required for unit power production by minimizing silicon consumption through silicon quantum dots and minimizing silicon consumption Efforts are being made.

  In the production of such silicon quantum dot solar cells and silicon thin film solar cells, the growth of silicon thin films doped with semiconductor elements is quite important for improving the performance of solar cells, and the existing methods are thermal diffusion and chemical vapor deposition. However, there is a limitation in adjusting the doping concentration, and a special method for high concentration doping is required.

  The present invention provides a method for manufacturing an n-type semiconductor quantum dot-based solar cell in which n-type impurities are doped at a high concentration using a compound target, and reproducible impurity element doping is possible. The present invention provides a method of manufacturing an n-type semiconductor quantum dot-based solar cell having high efficiency by a considerably simple and easy method.

  The present invention relates to a method for manufacturing a semiconductor quantum dot solar cell. In the method for manufacturing a quantum dot solar cell according to the present invention, a semiconductor layer containing a group 4 element and InP is formed on a substrate, and then the semiconductor layer is formed. The substrate is heat-treated to remove In, and includes a quantum dot forming step of forming an n-type semiconductor quantum dot that is a group 4 element quantum dot doped with P (phosphorus).

  In the heat treatment, the removal of In is characterized by removal by volatilization (volatilization from solid to gas).

  Characteristically, the semiconductor layer is a group 4 element or a compound of a group 4 element physically doped with the InP.

  Characteristically, the semiconductor layer includes an amorphous phase doped with InP, and the amorphous phase doped with InP is an amorphous phase of a group 4 element doped with InP. , An amorphous phase of a group 4 element oxide doped with InP, an amorphous phase of a group 4 element nitride doped with InP, or a mixture thereof.

  Characteristically, the semiconductor layer is a thin film of a group 4 element doped with InP, a thin film of a group 4 element nitride doped with InP, a thin film of a group 4 element oxide doped with InP, or a laminate thereof. It is a thin film.

  The semiconductor layer containing the group 4 element and InP is formed by physical vapor deposition. In detail, the physical vapor deposition is sputtering, and the sputtering is performed by using a group 4 element target and InP. The target is characterized by being deposited by simultaneous sputtering using an ion beam.

  The group 4 element is characterized in that it is one or more elements selected from Si and Ge, and the temperature of the heat treatment performed in the quantum dot formation step is in the range of 900 ° C. to 1150 ° C.

  Preferably, the manufacturing method of the present invention includes: a) a step of alternately stacking a medium layer and the semiconductor layer on a p-type semiconductor substrate to form a composite stacked layer; and b) heat-treating the composite stacked layer to form a semiconductor. Forming an in-medium P-doped semiconductor quantum dot that is a nitride, a semiconductor oxide or a mixture thereof; and c) heat-treating in a hydrogen atmosphere to form the P (phosphorus) -doped semiconductor quantum dot. Combining non-bonded electrons with hydrogen.

  At this time, the semiconductor layer may be a group 4 element thin film doped with InP, a group 4 element nitride thin film doped with InP, a group 4 element oxide thin film doped with InP, or a laminated thin film thereof. The medium layer is characterized in that it is a nitride of a group 4 element, an oxide of a group 4 element, or a mixture thereof independently of the semiconductor layer.

  At this time, the thickness of the medium layer and the semiconductor layer is preferably 0.5 nm to 5 nm independently of each other.

  In the manufacturing method according to the present invention, after the quantum dot forming step, an electrode forming step of forming two electrodes facing each other across the substrate and the n-type semiconductor quantum dot and at least one electrode being a transparent electrode is further performed. Preferably, a polycrystalline semiconductor layer which is a polycrystalline group 4 semiconductor layer doped with a group 3 or group 5 element is further formed between the n-type semiconductor quantum dot and the transparent electrode. Further preferred.

  The method for manufacturing a quantum dot solar cell according to the present invention can adjust the doping concentration of P by physical forced injection by using an InP compound as an n-type impurity for manufacturing an n-type semiconductor quantum dot. There is an advantage that an n-type semiconductor quantum dot doped with P at a considerably high concentration can be manufactured, and there is an advantage that high purity P doping is possible by completely removing In by heat treatment.

  In addition, there is an advantage that n-type semiconductor quantum dots of various sizes can be included in an n-type region forming a pn junction, and a compound target that is stable at room temperature for n-type doping. (Target) enables reproducible impurity element doping, impurity element doping under relaxed process conditions, and considerably high concentration of impurities by a considerably simple and easy method of sputtering and heat treatment Can be manufactured, and a solar cell having excellent light absorption efficiency can be manufactured.

It is one process figure which shows the manufacturing method of the quantum dot solar cell by this invention. It is another one process figure which shows the manufacturing method of the quantum dot solar cell by this invention. It is another one process figure which shows the manufacturing method of the quantum dot solar cell by this invention. It is a SIMS depth distribution analysis result with respect to O, Si, and P before and after heat treatment of a semiconductor layer. It is a SIMS depth distribution analysis result with respect to O, Si, and In before and after heat treatment of a semiconductor layer. It is the result of measuring the efficiency of the quantum dot solar cell by this invention, and is the efficiency measurement result of the quantum dot solar cell manufactured by laminating | stacking an electrode on a polycrystalline silicon layer after removing a surface oxide film. It is the result of measuring the efficiency of the quantum dot solar cell according to the present invention, the result of measuring the photoelectric efficiency of the solar cell element in which an 80 nm ITO thin film was formed as a transparent conductive film on the polycrystalline silicon layer after removing the surface oxide film It is.

  Hereinafter, the manufacturing method of the present invention will be described in detail with reference to the accompanying drawings. The drawings presented below are provided by way of example so that those skilled in the art can fully communicate the spirit of the present invention. Therefore, the present invention is not limited to the drawings presented below, and may be embodied in other forms. The drawings presented below are for clarifying the idea of the present invention. It can be exaggerated and illustrated. Also, the same reference numerals throughout the specification indicate the same components.

  At this time, if there is no other definition in the technical terms and scientific terms used, it has the meaning normally understood by those having ordinary knowledge in the technical field to which this invention belongs, and the following explanation and attached In the drawings, descriptions of known functions and configurations that obscure the gist of the present invention are omitted.

  FIG. 1 is an example of a process diagram showing a quantum dot formation stage in the manufacturing method according to the present invention, as shown in FIG. A semiconductor layer 120 containing InP and a Group 4 element is formed on the substrate 110, and then the substrate 110 on which the semiconductor layer 120 is formed is subjected to a heat treatment to form a quantum dot of a Group 4 element doped with P. The semiconductor quantum dot layer 130 in which the n-type semiconductor quantum dots 132 are contained in a medium 131 containing a group 4 element is manufactured.

  Specifically, the semiconductor layer 120 is a group 4 element, a group 4 element oxide, a group 4 element nitride, a mixture thereof, or a film in which InP is forcibly doped as an impurity in a laminated thin film thereof. The semiconductor layer 120 includes a group 4 element, a group 4 element oxide, a group 4 element nitride, and a mixture thereof in an amorphous phase. InP contained in the layer is characterized in that In is selectively evaporated (evaporation from solid to gas) and the n-type semiconductor quantum dots 132 are formed.

  In detail, during the heat treatment of the semiconductor layer 120 which is a film in which InP is forcibly doped, only the In is selectively evaporated and removed by the difference in vapor pressure in the semiconductor layer 120, and the quantum of the group 4 element doped purely with P There is a feature that an n-type semiconductor quantum dot 132 which is a dot is formed.

  Since the InP is a compound that is stable at room temperature, the semiconductor layer 120 is a film in which InP is forcibly doped as an impurity by a physical vapor deposition method using an InP target and a target of a group 4 element. There is a feature that the semiconductor layer 120 can be manufactured, and the semiconductor layer 120 can be doped with InP at a considerably high concentration, and the semiconductor layer 120 can be doped with InP at a precisely controlled concentration.

  Specifically, the semiconductor layer 120 is performed by physical vapor deposition, and the physical vapor deposition is characterized by sputtering. More specifically, the sputtering for forming the semiconductor layer 120 is performed by using a thin InP target and a thin group IV. There is a feature that is performed using a method in which an element target is simultaneously sputtered and deposited.

  At this time, the concentration of InP contained in the semiconductor layer 120 formed on the substrate 110 is controlled by the relative sputtering area or ion beam intensity of the InP target and the Group 4 element target used during sputtering. It is preferable.

  Specifically, the group 4 element is characterized in that it is Si, Ge or SiGe compound, and the substrate is a p-type semiconductor substrate. At this time, the p-type semiconductor substrate is preferably a substrate in which a p-type impurity is doped in the same element as the Group 4 element included in the semiconductor layer 120.

  Preferably, the semiconductor layer 120 is a group 4 element thin film in which InP is forcibly doped as an impurity in a group 4 element oxide, a group 4 element nitride, a mixture thereof, or a laminated thin film thereof. Accordingly, the semiconductor quantum dot layer 130 manufactured by the heat treatment has a plurality of n-type semiconductor quantum dots 132 arrayed in a medium 131 that is a Group 4 element oxide, a Group 4 element nitride, or a mixture thereof. And having a structure included in the medium.

  FIG. 2 is a preferred process diagram showing the manufacturing method of the present invention. The substrate 110, preferably a p-type semiconductor substrate, and the semiconductor layer detailed on the basis of FIG. 122 is alternately deposited to produce a composite laminated layer 120 'having a multilayer thin film structure, and then a pure group 4 element layer 123 is deposited on the surface in order to facilitate the deposition of the transparent conductive film. A group element oxide layer 124 is deposited.

  The medium layer 121 is characterized by being an oxide of a group 4 element, a nitride of a group 4 element, or a mixture thereof, and the plurality of medium layers 121 constituting the composite stacked layer 120 ′ are different from each other depending on the film. It may have a material (semiconductor oxide, semiconductor nitride, a mixture of semiconductor oxide and semiconductor nitride) and different thicknesses.

  Preferably, when the Group 4 element of the semiconductor layer 122 is an oxide phase, the medium layer 121 is also preferably an oxide phase, and when the Group 4 element of the semiconductor layer 122 is a nitride phase, the medium Layer 121 is also preferably a nitride phase.

  Since the n-type semiconductor quantum dots 132, which are P-doped group 4 element quantum dots, are formed by the heat treatment of the semiconductor layer 122, the thickness of the semiconductor layer 122, the composition of the semiconductor layer 122, The position, size, number, etc. of the n-type semiconductor quantum dots 132 in the medium 131 are controlled by the number of the semiconductor layers 122 constituting the composite stacked layer 120 ′.

  Specifically, it is preferable to deposit the medium layer 121 and the semiconductor layer 122 so that the thickness of the composite layer 120 ′ is 0.5 nm to 5 nm, respectively.

  Also, the thickness of the composite multilayer layer 120 ′ is several nanometers to several hundred nanometers, and the semiconductor quantum dot layer 130 produced by heat treatment of the composite multilayer layer 120 ′ has a thickness of several nanometers to several hundreds. It is preferable to control to be nanometer.

  Thereafter, as in the description of FIG. 1, the composite stacked layer 120 ′ is heat-treated, and a semiconductor in which a plurality of n-type semiconductor quantum dots 132 in the medium 131 and a polycrystalline group 4 element layer 133 are formed on the surface. The quantum dot layer 130 is formed.

  In is selectively removed by the heat treatment, and an n-type semiconductor quantum dot 132 array surrounded by a medium is manufactured by using stress relaxation and interface energy minimization as a driving force to form an n-type semiconductor quantum dot 132 array. Thereafter, re-heat treatment is performed in a hydrogen atmosphere to bond non-bonded electrons of the n-type semiconductor quantum dots 132 to hydrogen.

  The heat treatment for forming the n-type semiconductor quantum dots 132 must be determined in consideration of the selective evaporation removal of In, the material of the medium, the material of the semiconductor layer, and the size and density of the quantum dots to be manufactured. The main consideration is the selective removal of In and the generation of an n-type semiconductor quantum dot having a quantum confinement effect. For this reason, the heat treatment for forming the n-type semiconductor quantum dot 132 is 900 It is preferable to be carried out at a temperature between 1C and 1150C.

  When the n-type semiconductor quantum dots are manufactured, if the heat treatment temperature is too low, In is not removed, mass transfer is difficult and it is difficult to obtain a semiconductor quantum dot shape, and only the heat treatment temperature is too high In addition, there is a risk that P is also removed, there is a risk that the size of the semiconductor quantum dots will be considerably non-uniform, and there is a risk that coarse particles with a slight quantum confinement effect will be generated.

Specifically, the heat treatment for forming the n-type semiconductor quantum dots 132 is performed at 1100 ° C. to 1150 ° C. when a group 4 element oxide, preferably silicon oxide (SiO ₂ ), is used as a semiconductor nitride. Preferably, when silicon nitride (Si ₃ N ₄ ) is the medium, the heat treatment is preferably performed at 900 ° C. to 1100 ° C., and the heat treatment is preferably performed for 10 minutes to 30 minutes.

Thereafter, a hydrogenation step is performed in which heat treatment is performed in a hydrogen atmosphere to bond non-bonded electrons of the n-type semiconductor quantum dots to hydrogen. The heat treatment temperature in the hydrogenation step must be determined according to the type of semiconductor quantum dots. When the semiconductor quantum dots are silicon quantum dots, a forming gas (95% Ar-5% H ₂ ) is used. Heat treatment is preferably performed at a temperature of 600 ° C. to 700 ° C. for 30 minutes to 90 minutes in the hydrogen atmosphere used.

  Thereafter, as shown in FIG. 2, after the transparent conductive film 210 is formed on the heat-treated semiconductor layer 130, electrodes 310 and 320 are formed on the transparent conductive film 210 and the substrate. It is preferable. The electrodes 310 and 320 are manufactured using a normal printing method such as screen printing using a conductive metal paste, stencil printing, or vapor deposition using PVD / CVD.

  FIG. 3 is a more preferred process diagram illustrating the manufacturing method of the present invention. As shown in FIG. 3, the manufacturing method according to the present invention includes forming the composite stacked layer 120 ′ and then forming the composite stacked layer 120 ′. It is preferable to further form a group 4 element layer 123 on the upper surface, and further to form a surface oxide layer 124 which is an oxide layer of a group 4 element on the group 4 element layer 123.

  The group 4 element layer 123 is a thin film in which a group 3 or group 5 element is doped as an impurity in a pure group 4 element matrix that is not oxidized or nitrided. It is a group 4 element thin film. As an example, the group 4 element layer is a polycrystalline silicon layer. At this time, when the substrate 110 is a p-type substrate, the group 4 element layer 123 is preferably doped as an n-type impurity.

  The group 4 element layer 123 performs a role of facilitating the deposition of the transparent conductive film 210 by smoothly moving the flow of electrons and holes formed by the quantum dots 132 to the electrodes. In order to prevent a smooth flow of photocharge and annihilation due to recombination of photocharge, the group 4 element layer 123 preferably has a thickness of 30 nm to 50 nm.

  The surface oxide layer 124 is preferably a complete oxide phase of a group 4 element combined with chemically determined oxygen, and performs a role of protecting the photoactive region and the charge transfer region of the solar cell during heat treatment. To do. Since the surface oxide layer 124 must be removed after the heat treatment, the thickness is preferably 20 nm or more, and substantially 20 nm to 50 nm.

  Thereafter, similarly to the description of FIG. 2, the oxide layer 124 uses an etching solution after heat-treating and hydrogenating the composite laminated layer 120 'on which the group 4 element layer 123 and the surface oxide layer 124 are formed. It is preferably removed by wet etching.

  After the oxide layer 124 is removed, a transparent conductive film 210 is formed on the group 4 element layer 133 so as to be in contact with the group 4 element layer 133 exposed on the surface, and then the upper part of the transparent conductive film 210 and the substrate. It is preferable to form the electrodes 310 and 320 below the substrate.

  FIG. 4 shows SIMS depth distribution analysis results for O, Si, and P elements after heat treatment at 1100 ° C. for 20 minutes, and before and after heat treatment of the composite laminated layer manufactured as shown in FIG. These are SIMS depth distribution analysis results for O, Si, and In elements before and after heat treatment.

  As shown in FIG. 4 and FIG. 5, it is confirmed that the heat treatment completely removes In to such an extent that the analyzer can detect the deposited amount, and that P is maintained as it is. did it.

  FIG. 6 shows that an amorphous Si film doped with InP using sputtering is used as a semiconductor layer (1 nm), silicon oxide is used as a medium layer (2 nm), and the semiconductor layer and the medium layer are repeated 33 times. After stacking to form a composite stacked layer, an InP-doped amorphous silicon layer (30 nm) and a silicon oxide layer (20 nm) are formed, followed by heat treatment at 1100 ° C. for 20 minutes, and 600 ° C. in a hydrogen atmosphere. After removing the surface oxide film 134 with a BOE solution for the quantum dot solar cell produced by hydrogenating at 30 minutes, the efficiency measurement result of the solar cell in which the electrode is laminated on the group 4 element layer 133 is shown. FIG. 7 shows the result of measuring the photoelectric efficiency of a solar cell element in which an ITO thin film of about 80 nm is applied as a transparent conductive film on the group 4 element layer 133 on an element similar to FIG. If it was confirmed efficiency of about 25%.

  As described above, the present invention has been described with specific matters and limited embodiments and drawings. However, the present invention is only provided for a more general understanding of the present invention, and the present invention is not limited to the above. The present invention is not limited to the embodiments, and various modifications and variations can be made from such descriptions by those who have ordinary knowledge in the field to which the present invention belongs.

  Accordingly, the spirit of the present invention should not be determined by being limited to the embodiments described, but is limited not only to the claims described below, but also to all modifications that are equivalent or equivalent to the scope of the claims. Belongs to the category of thought.

DESCRIPTION OF SYMBOLS 110 Substrate 120 Composite laminated layer 121 Medium layer 122, 123 Semiconductor layer 130 Quantum dot layer 131 Medium 132 Quantum dot 133 Group 4 element layer 134 Surface oxide layer 210 Transparent conductive film 310, 320 Electrode

Claims (13)

In the method of manufacturing a semiconductor quantum dot-sensitized solar cell,
After forming a semiconductor layer containing a Group 4 element and InP on the substrate, the substrate on which the semiconductor layer is formed is heat-treated to remove In (Indium), and a Group 4 element quantum doped with P (phosphorus) The manufacturing method of the quantum dot solar cell characterized by including the quantum dot formation step which forms the n-type semiconductor quantum dot which is a dot.   2. The method of manufacturing a quantum dot solar cell according to claim 1, wherein the semiconductor layer is physically doped with a group 4 element or a compound of a group 4 element.   The method of claim 1, wherein the semiconductor layer includes an amorphous phase doped with InP.   The semiconductor layer is a thin film of a group 4 element doped with InP, a thin film of a group 4 element nitride doped with InP, a thin film of a group 4 element oxide doped with InP, or a laminated thin film thereof. The manufacturing method of the quantum dot solar cell of Claim 1 characterized by these.   The method for manufacturing a quantum dot solar cell according to claim 1, wherein the semiconductor layer containing the Group 4 element and InP is formed by physical vapor deposition.   6. The physical vapor deposition according to claim 5, wherein the physical vapor deposition is sputtering, and the sputtering is performed by simultaneously sputtering a group 4 element target and an InP target using an ion beam. Manufacturing method of quantum dot solar cell. a) alternately stacking a medium layer and the semiconductor layer on the p-type semiconductor substrate to form a composite stacked layer;
b) heat treating the composite stack to form in-medium P (phosphorus) doped semiconductor quantum dots that are semiconductor nitride, semiconductor oxide, or a mixture thereof;
c) heat treating in a hydrogen atmosphere to bond non-bonded electrons of the P (phosphorus) doped semiconductor quantum dots with hydrogen;
The manufacturing method of the quantum dot solar cell of Claim 1 characterized by the above-mentioned.   The semiconductor layer is a thin film of a group 4 element doped with InP, a thin film of a group 4 element nitride doped with InP, a thin film of a group 4 element oxide doped with InP, or a laminated thin film thereof. 8. The method of manufacturing a quantum dot solar cell according to claim 7, wherein the medium layer is a nitride of a group 4 element, an oxide of a group 4 element, or a mixture thereof independently of the semiconductor layer.   The method for manufacturing a quantum dot solar cell according to claim 7, wherein the thickness of the medium layer and the semiconductor layer is independently 0.5 nm to 5 nm.   After the quantum dot forming step, an electrode forming step of forming two electrodes facing each other across the substrate and the n-type semiconductor quantum dot and at least one electrode being a transparent electrode is further performed. The manufacturing method of the quantum dot solar cell of Claim 1 or 7.   11. A polycrystalline semiconductor layer, which is a polycrystalline group 4 semiconductor layer doped with a group 3 or group 5 element, is further formed between the n-type semiconductor quantum dot and the transparent electrode. The manufacturing method of the quantum dot solar cell of description.   The method for manufacturing a quantum dot solar cell according to claim 1, wherein the heat treatment is performed at 900 ° C. to 1150 ° C.   The method for manufacturing a quantum dot solar cell according to claim 1, wherein the group 4 element is an element selected from one or more of Si and Ge.

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